The present invention generally relates to windows and the like for motor vehicles. More specifically, the present invention relates to motor vehicle panes for such windows that include a sheet of glass preferably consisting of a single silicate glass sheet or of a lamination with silicate glass covering sheets, and which include from the side facing the inside of the vehicle when the pane is positioned in the vehicle, a plastic-deformable lamination film made of polyvinylbutyral or similar material and an adjoining splinter protection film made of polyester or similar material. Preferably, these panes are equipped on the inside face with a scratch-resistant coating. A frame gasket made of plastic material, such as polyurethane or similar material, integrally cast, injection moulded, moulded and/or glued on in situ, extends around the peripheral edge of the sheet of glass, which is glued to the splinter protection film by means of the lamination film. The frame gasket encloses the width of the peripheral edge surface as well as an area of the side surfaces close to the peripheral edge on the one hand of the sheet of glass and on the other of the splinter protection film.
When the progressive development of motor vehicles, safety for the occupants, or passengers, of the motor vehicle has, likewise, also improved. One area of improvement in the safety of the vehicle's passengers has included making the motor vehicle's windows safer. Vehicle windows have progressed from simple glass sheet panes originally found in motor vehicles, to the development of thermally toughened glass and more recently, the development of laminated safety glasses. Through these developments and improvements in the glass panes, the risk of injury to the vehicle pasengers from the windows during a collision or accident has been continually reduced.
However, even though thermally toughened glass and laminated glass have reduced the risk of injury to passengers during collisions or accidents, there is still a risk of passengers being cut if the passenger impacts the sheet of glass in the windows, e.g., if the passenger impacts the windshield of the car. For this reason, more recent developments in this area have moved toward building motor vehicle glass panes of various designs, some of which have a coating made of a single or multilayer plastic material on the inner side of the silicate glass sheet or a lamination made of silicate glass sheets, in an attempt to avoid the risk of cuts to the occupants of the vehicle during collisions.
One of these developments has, for example, led to the use of a thin polyester film being applied on the side of the glass sheet that faces the inside of the vehicle, when the glass sheet is positioned in the vehicle, which is joined to the sheet of glass by polyvinylbutyral film. The polyester film is coated with methylsiloxane to make it abrasion-proof. This construction however has numerous disadvantages. The scratch-resistant coated polyester film cannot be firmly attached to the body of the vehicle with conventional fitting devices in motor vehicle glazing. Accordingly, the advantages of the laminated safety glass pane are lost. For example, in the event of the impact of the head of an occupant of the motor vehicle against the glass pane, the lamination materials elastically decelerates the passenger's head so that excessive acceleration of the skull and the associated risk to health are for the most part avoided. However, as a result of the lack of adhesion in the fitting media, the lamination layer frees itself from the body of the vehicle. The passenger is therefore not restrained, but instead forces the motor vehicle's glass pane out of the bodywork because of the force of his acceleration. This results in an increased risk of injury to the passenger.
A motor vehicle glass pane is disclosed in DE-OS No. 35 21 115. The glass pane includes a lamination film and splinter protection film made of polyester, which may have a scratchresistant coating. The films are aligned, in principle, on their peripheral borders with the peripheral border of the sheet of glass. The frame gasket, made of polyurethane, is directly moulded thereon. In this case however, the bond with the frame gasket and the glass pane is produced solely by the adhesion between the polyurethane and the sheet of glass or the splinter protection film. Although this construction prevents glass splinters from being released from the glass sheets during a collision or other accident it does not, however, prevent the glass pane, or the splinter protection film, from being torn out from the frame when impacted by the body of the passenger during a collision. The construction of the glass pane and frame gasket do not allow the forces exerted by the passenger's body to be absorbed. The disclosed motor vehicle glass pane therefore does not function entirely satisfactorily inasmuch as the elastic deformable lamination film cannot elastically decelerate a motor vehicle passenger when the passenger impacts the glass pane during a collision.
DE-OS No. 35 90 207 also discloses a motor vehicle glass pane of the similar type to and with similar disadvantages to those described and discussed above in DE-OS No. 35 21 115.
In order to be able to reliably reduce the impact energy of the motor vehicle passenger during a collision or accident the window pane should act as a safety net to decelerate the passenger during impact. To this end, it is necessary for the plastic coating to be firmly joined to the body of the vehicle along its edges. Conventional polyurethane installation adhesives are compatible with plastic coatings, thus the adhesive sticks to the plastic coating well. In the case of the hard scratch-resistant coating typically used in motor vehicle glass panes neither the material of the frame gasket, during moulding, nor, in the case of gluing, conventional adhesives stick sufficiently well to the polyester film, especially polyester film which is hardened on the surface of the pane.
A method is known from U.S. Pat. No. 2,379,194, with which laminated glasses can be fitted in aircraft in such a way that the compressive forces which occur in the pressurized cabins of aircraft which fly at great heights, can be absorbed. To this end, the plastic film is allowed to protrude beyond the edge of the silicate glass sheets. The overlapping area of the film is used to produce a tight joint in the outer skin of the aircraft. In connection with this, the difficulty of having to produce a sufficiently tight pressed gasket on thick, relatively irregular sheets as a result of the tolerances of the production technique is avoided. Because of the viscoelastic properties of the film, the stress acting vertically on the film is converting into shearing stress in the film with the aid of additional inserts, whereby the property of the film of being highly resistant to shearing action, is exploited. In order to prevent the glass sheet, which is only embedded in the external skin of the aircraft via the thermoplastic intermediate layer, from being pressed outwards out of the aircraft at great heights under the static pressure on the inside of the aircraft, a reinforcing element is inserted in the area of the overlapping film so that in this way fixing of the sheets of glass parallel to the outer skin of the aircraft is ensured.
DE-OS No. 22 47 644 discloses a motor vehicle glass pane in which the glass unit is glued to the frame, which can then surround both the sheet of glass as well as an applied plastic coating. However the problem of a sufficient transmission of the impact energy from the plastic-deformable lamination film to the body of the vehicle in the event of impact is not overcome because the plastic materials adhere poorly with the adhesive or the frame material.
U.S. Pat. No. 2,572,947 shows a laminated glass pane structure, in which a plastic film arranged between two sheets of glass is fitted with projections protruding from the plane of the glass sheet. The projections function to secure the glass unit in the frame. However, for example, when the glass pane is used in aircraft windows, the projections provided therein make a relatively thick glass pane construction necessary. This large thick construction prevents usage of the glass panes in typical motor vehicles of modern design.
There is therefore a need for an improved glass pane for motor vehicles.